"A systematic approach to understanding the basics of Voice over IP -- Fully Updated and Revised!. New edition of the best-selling 1st edition promotes understanding of voice application and services. Complete coverage examines all basic VoIP signaling protocols and primary legacy voice signaling protocols . Demonstrates how all the various voice technologies integrate to form a cohesive system . Updates readers with new chapters and topics including security This book is a complete revision of the best-selling, well-respected first edition (1578701686). The continued focus of Voice over IP Fundamentals is to bring users, implementers, and developers of this technology up to a basic level of understanding of the marketplace, history, and future of VoIP. This is accomplished through thorough updates to technical data and examination of new applications that have become popular over the past years. Areas for future growth are also explored. This new edition focuses on the many changes that have occurred in basic technology and new applications using that technology. For example, the first version of this book published when SIP was a new and unknown technology. SIP is now seen as the ideal control protocol for voice traffic and other real time media streams. Additionally, new applications combining legacy services with new services are being deployed. One example of these services is the combination of telephony services and presence applications. As there are multiple titles in the marketplace that address how to specifically implement a given technology, this book focuses primarily on the technology and applications. This second edition features brand-new chapters on billing and mediation services, voice security, IP and PSTN internetworking, and applications chapters for both enterprises and service providers."